1. Field of the Invention
This invention relates to a zoom lens assembly for a photographic camera, and more particularly to a zoom lens assembly capable of changing over automatic focusing and manual focusing by a simple operation.
2. Related Background Art
The well-known one-hand zoom lens assembly is such that zooming is accomplished by moving an operating ring in the direction of the optic axis and focusing is accomplished by rotating the operating ring. If the conventional focus adjusting mechanism in a single-lens reflex camera is intactly adopted in the zoom lens assembly of this type, the operating ring will rotate during automatic focus adjustment to prove a hindrance to the holding of the lens barrel and make it impossible to effect the zooming operation simultaneously with automatic focus adjustment.
There is also known a zoom lens assembly capable of automatic focus adjustment which is provided with a zoom ring rectilinearly movable in the direction of the optic axis for the zooming operation and a focus ring rectilinearly movable therewith and rotatable about the optic axis for focus adjustment. Again in such a zoom lens assembly, the focus ring rotates during automatic focus adjustment and therefore, if the focus ring is touched inadvertently, automatic focus adjustment will be adversely affected. Also, it is conceivable to form the focus ring itself with a narrow width so as to prevent the focus ring from being touched inadvertently, but this is not preferable in that the operability for manual focus adjustment becomes worse.